Quote:
Originally Posted by Nexin
Both classic and Virtualdub2 support output only AVI and WAV. There is external encoders but the ID change again to FF reason I wonder if Virtualdub at fault or the AAC_ACM codec.
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Can't agree on that, as far as Virtualdub
2 is concerned:
https://i.imgur.com/mkzKxPH.png
Quote:
Originally Posted by Nexin
Yes maybe but the FF once written even when muxed to mp4 remains.
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Keep in mind that "wFormatTag" (aka "TwoCC") is used
only in WAV/AVI containers.
Even though
0xFF appears to be the "correct" TwoCC value for AAC streams in WAV/AVI containers, there simply is
no such thing as "TwoCC" (wFormatTag) field in MP4 container.
So, I don't know
which exact "ID" you are looking at, when you are talking about the MP4 file, or how you are extracting
that ID from the MP4 file.
But: If you are 100% certain that you are looking at the
ObjectTypeIndication in the "esds" atom of the MP4 file, then this definitely should be
0x40 for "MPEG-4 Audio" streams. And the
AudioObjectType should be
2, for LC-AAC.
Example:
https://i.imgur.com/3LZYXIV.png
Anyways, a "wrong"
ObjectTypeIndication in the MP4 file would be the fault of the MP4
muxing software, which was used to re-mux the AAC stream from the AVI to the MP4 container –
not that of VirtualDub or the ACM Codec.